Provided is a sealing device capable of exhibiting a screw pumping effect in an early stage while inhibiting leakage of a fluid to be sealed by providing thread protrusions. A second inclined surface is provided with a plurality of first thread protrusions that cause a fluid to be sealed to flow toward a region to be sealed when the seal lip rotates in one direction relative to a shaft, and a plurality of second thread protrusions that cause the fluid to be sealed to flow toward the region to be sealed when the seal lip rotates in another direction relative to the shaft. In a state before progress of sliding wear on the seal lip, a sidewall of each of the first thread protrusions on a side facing the region to be sealed and a sidewall of each of the second thread protrusions on the side facing the region to be sealed are both designed to be parallel to a center axis line of the shaft in a state in which the seal lip is in contact with a surface of the shaft.
|
2. A sealing device, comprising:
a seal lip that is configured to slide on a surface of a shaft that rotates relative to the sealing device,
the seal lip having a lip end formed of a first inclined surface that is configured to radially expand towards a region to be sealed and a second inclined surface that is configured to radially expand towards an opposite side to the region to be sealed,
the second inclined surface being provided with a plurality of first thread protrusions that is configured to cause a fluid to be sealed to flow toward the region to be sealed as a result of the seal lip rotating in one direction relative to the shaft, and a plurality of second thread protrusions that is configured to cause the fluid to be sealed to flow toward the region to be sealed as a result of the seal lip rotating in another direction relative to the shaft, and
in a state before progress of sliding wear on the seal lip,
a sidewall, which is nearest the lip end, of each of the first thread protrusions and a sidewall, which is nearest the lip end, of each of the second thread protrusions both being configured to extend parallel to a surface of the shaft in a state in which the seal lip is in contact with a surface of the shaft.
1. A sealing device comprising:
a seal lip that is configured to slide on a surface of a shaft that rotates relative to the sealing device,
the seal lip having a lip end formed of a first inclined surface that is configured to radially expand towards a region to be sealed and a second inclined surface that is configured to radially expand towards an opposite side to the region to be sealed,
the second inclined surface being provided with a plurality of first thread protrusions that is configured to cause a fluid to be sealed to flow toward the region to be sealed as a result of the seal lip rotating in one direction relative to the shaft, and a plurality of second thread protrusions that is configured to cause the fluid to be sealed to flow toward the region to be sealed as a result of the seal lip rotating in another direction relative to the shaft, and
in a state before progress of sliding wear on the seal lip,
a sidewall, which is nearest the lip end, of each of the first thread protrusions and a sidewall, which is nearest the lip end, of each of the second thread protrusions both being configured to extend parallel to a center axis line of the shaft in a state in which the seal lip is in contact with a surface of the shaft.
|
The present disclosure relates to a sealing device provided with thread protrusions that exhibit a screw pumping effect.
For a sealing device such as an oil seal, it is a known technique to provide thread protrusions that exhibit a screw pumping effect on an inclined surface of a lip end of a seal lip on the opposite side to a region to be sealed in order to cause a fluid to be sealed leaking from the lip end of the seal lip back toward the region to be sealed. It is also a known technique, for a configuration in which a shaft rotates in both directions relative to the seal lip (sealing device), to provide thread protrusions that exhibit a screw pumping effect when the shaft rotates in a forward direction, and thread protrusions that exhibit a screw pumping effect when the shaft rotates in a reverse direction. With this technique, sometimes, the thread protrusions for reverse rotation could become the cause of leakage during the rotation in the forward direction, and the thread protrusions for forward rotation could become the cause of leakage during the rotation in the reverse direction. This issue is explained with reference to
This sealing device is provided with thread protrusions 720 that exhibit a screw pumping effect on an inclined surface 710 of a lip end of a seal lip 700 on the opposite side (A) to a region to be sealed (O). The thread protrusions 720 are configured to rise vertically from the inclined surface 710.
In the sealing device configured as described above, conventionally, the thread protrusion 720 is designed to have an end portion on the side facing the region to be sealed (O) in contact with the surface of the shaft in a state before the progress of sliding wear on the seal lip 700 so that the screw pumping effect is exhibited from an early stage of use. The dot line 500X in
However, another issue with this technique is that the function that the thread protrusions are supposed to provide, i.e., the screw pumping effect, is not fully exhibited because the thread protrusions 720 are spaced from the surface of the shaft 500 in the state before the progress of sliding wear on the seal lip 700. Namely, there is still some scope of improvement.
An object of the present disclosure is to provide a sealing device capable of exhibiting a screw pumping effect in an early stage while inhibiting leakage of a fluid to be sealed by providing thread protrusions.
The present disclosure adopts the following means to achieve the object noted above.
Namely, a sealing device according to the present disclosure is a sealing device including
According to the present disclosure, in the state before the progress of sliding wear on the seal lip, there is no step formed between an end (edge) portion of each thread protrusion on the side facing the region to be sealed and the second inclined surface, and even in a state in which the thread protrusions are in contact with the surface of the shaft, no gaps resulting from the existence of the thread protrusions are formed. This in turn allows the gap between the thread protrusions and the shaft to be minimum possible (or to be eliminated) in a state before the progress of sliding wear on the seal lip while leakage resulting from the thread protrusions is suppressed. Accordingly, by making this gap to be minimum possible (or to be eliminated) in a state before the progress of sliding wear on the seal lip, the screw pumping effect can be achieved in an early stage (or immediately in the case where the gap is eliminated).
As described above, according to the present disclosure, a screw pumping effect can be exhibited in an early stage while leakage of a fluid to be sealed is inhibited by providing thread protrusions.
Modes for carrying out this disclosure will be described in detail hereinafter illustratively based on specific embodiments with reference to the drawings. It should be noted that, unless otherwise particularly specified, the sizes, materials, shapes, and relative arrangement or the like of constituent components described in the embodiments are not intended to limit the scope of this disclosure. The sealing device according to this embodiment may be favorably used for sealing purposes in various devices such as robots and servomotors for sealing a fluid to be sealed such as oil.
A sealing device according to one embodiment of the present disclosure is described with reference to
<Sealing Structure>
A sealing structure that has the sealing device 10 according to this embodiment is described with reference, in particular, to
<Sealing Device>
The sealing device 10 is described in more detail with reference, in particular, to
The seal main body 200 includes an integrally formed seal lip 210 and a dust lip 220, the seal lip extending from the distal end of the inward flange part 120 radially inward and toward the region to be sealed (O) and making slidable close contact with the surface of the shaft 500, and the dust lip being located closer to the opposite side (A) to the region to be sealed (O) than the seal lip 210. The lip end of the seal lip 210 is formed of a first inclined surface 211 radially expanding toward the region to be sealed (O) and a second inclined surface 212 radially expanding toward the opposite side (A) to the region to be sealed (O). A garter spring 300 is mounted on the radially outer side of the seal lip 210 to press the lip end against the surface of the shaft 500.
The second inclined surface 212 is provided with thread protrusions that exhibit a screw pumping effect.
<Thread Protrusion>
The thread protrusions provided to the second inclined surface 212 are described with reference, in particular, to
More specifically, the second inclined surface 212 is provided with a plurality of first thread protrusions 213 that cause the fluid to be sealed to flow toward the region to be sealed (O) when the seal lip 210 rotates in one direction relative to the shaft 500. The second inclined surface 212 is also provided with a plurality of second thread protrusions 214 that cause the fluid to be sealed to flow toward the region to be sealed (O) when the seal lip 210 rotates in the other direction relative to the shaft 500. Here, rotation of the seal lip 210 in the direction of arrow S in
In a state before the progress of sliding wear on the seal lip 210, a sidewall 213a of the first thread protrusion 213 on the side facing the region to be sealed (O) is designed to be parallel to the center axis line of the shaft 500 in the state in which the seal lip 210 is in contact with the surface of the shaft 500. In other words, in the state before the progress of sliding wear on the seal lip 210, the sidewall 213a of the first thread protrusion 213 on the side facing the region to be sealed (O) is designed to be parallel to the surface of the shaft 500 (see
Similarly, in the state before the progress of sliding wear on the seal lip 210, a sidewall 214a of the second thread protrusion 214 on the side facing the region to be sealed (O) is designed to be parallel to the center axis line of the shaft 500 in the state in which the seal lip 210 is in contact with the surface of the shaft 500. In other words, in the state before the progress of sliding wear on the seal lip 210, the sidewall 214a of the second thread protrusion 214 on the side facing the region to be sealed (O) is designed to be parallel to the surface of the shaft 500 (see
According to the sealing device 10 of this embodiment, in the state before the progress of sliding wear on the seal lip 210, there is no step formed between an end (edge) portion of each thread protrusion (first thread protrusion 213 and second thread protrusion 214) on the side facing the region to be sealed and the second inclined surface 212. That is, the distance T in
This in turn allows the gap between the thread protrusions and the shaft 500 (gap X in
As described above, the sealing device 10 according to the present disclosure can exhibit a screw pumping effect in an early stage while inhibiting leakage of the fluid to be sealed by providing the thread protrusions (first thread protrusions 213 and second thread protrusions 214).
(Others)
Although an embodiment has been described with respect to a sealing device having a dust lip 220 in addition to a seal lip 210, the sealing device of the present disclosure is not limited to this configuration. Namely, the sealing device of the present disclosure is applicable at least to various sealing devices having a seal lip provided with the first thread protrusions and second thread protrusions. The present disclosure can therefore be applied to a sealing device that does not include a dust lip, and to a sealing device that has an auxiliary seal lip additionally between a seal lip provided with thread protrusions and a dust lip. The present disclosure can also be applied to a sealing device having other configurations that, for example, further includes an end face lip slidable on an end face of a flange-shaped member fixed to the shaft. While one example of a sealing device that has a reinforcing ring has been described in the embodiment above, the sealing device of the present disclosure is applicable also to a sealing device that does not include a reinforcing ring.
Patent | Priority | Assignee | Title |
Patent | Priority | Assignee | Title |
4183543, | Nov 13 1978 | Dana Corporation | Hydrodynamic seal with collector bead |
5002289, | Jun 13 1988 | Koyo Seiko Co., Ltd. | Bi-directional oil seal with leakage recovering rib formations |
20180119820, | |||
20210010599, | |||
GB1556870, | |||
JP1019135, | |||
JP1019136, | |||
JP1312274, | |||
JP2003240126, | |||
JP2006189116, | |||
WO2020045070, |
Executed on | Assignor | Assignee | Conveyance | Frame | Reel | Doc |
Apr 15 2020 | NOK Corporation | (assignment on the face of the patent) | / | |||
Aug 16 2021 | MANAKA, YUTO | NOK Corporation | ASSIGNMENT OF ASSIGNORS INTEREST SEE DOCUMENT FOR DETAILS | 057802 | /0123 |
Date | Maintenance Fee Events |
Oct 15 2021 | BIG: Entity status set to Undiscounted (note the period is included in the code). |
Date | Maintenance Schedule |
Oct 03 2026 | 4 years fee payment window open |
Apr 03 2027 | 6 months grace period start (w surcharge) |
Oct 03 2027 | patent expiry (for year 4) |
Oct 03 2029 | 2 years to revive unintentionally abandoned end. (for year 4) |
Oct 03 2030 | 8 years fee payment window open |
Apr 03 2031 | 6 months grace period start (w surcharge) |
Oct 03 2031 | patent expiry (for year 8) |
Oct 03 2033 | 2 years to revive unintentionally abandoned end. (for year 8) |
Oct 03 2034 | 12 years fee payment window open |
Apr 03 2035 | 6 months grace period start (w surcharge) |
Oct 03 2035 | patent expiry (for year 12) |
Oct 03 2037 | 2 years to revive unintentionally abandoned end. (for year 12) |